1. Presented by: Kevin J. Spencer, P.G. R.W. Harden and Associates, Inc. Benefits and Challenges of Developing Brackish Groundwater Supplies WATER Supply

2. Objectives The Need to Develop Brackish Groundwater Supplies The Need to Develop Brackish Groundwater Supplies Potential Advantages Potential Advantages Practical Considerations Practical Considerations

3. City of Los Fresnos Indian Lake Port of Brownsville Valley MUD #2 Rio Grande Regional Water Planning Group Rio Grande Regional Water Planning Group Southmost Regional Water Authority

4. Surface Reservoir Conditions

9. What Can We Expect? Increased demand/less water Increased demand/less water Implementation of drought management strategies Implementation of drought management strategies Irrigation shortages Irrigation shortages –“Piggy Back” by municipalities –Hydrilla/ Hyacinth blockage

10. Alternative Sources Conservation Conservation Reuse Reuse Desalination Desalination –Sea Water –Brackish Groundwater

11. Brackish Groundwater Desalination Significant brackish groundwater reserves in Gulf Coast aquifers Significant brackish groundwater reserves in Gulf Coast aquifers Independent of river flows Independent of river flows Not subject to water rights purchases* Not subject to water rights purchases* Cost of treatment comparable to surface water Cost of treatment comparable to surface water Improved water quality Improved water quality

12. Cost Trends Cost per 1000 gallon including debt service and operations Source: NRS Consulting Engineers

13. Degree of total dissolved solids Degree of total dissolved solids Power costs Power costs Economies of scale Economies of scale Location Location Concentrate disposal Concentrate disposal Cost Factors

14. Advantages over sea water Advantages over sea water –Significant reduction in plant capital and O&M –Reduced environmental impact Advantages over surface water Advantages over surface water –Drought tolerant –Improved water quality –Water rights savings Brackish Groundwater

15. Advantages over fresh groundwater Advantages over fresh groundwater –New Supply Resource –Less Competition –Less Regulation –Positive Public Perception

16. Regional Water Supply Establish economies of scale Establish economies of scale Favorable to funding agencies Favorable to funding agencies –Texas Water Development Board policy statement –Infrastructure financing

17. Allocation of Water 7.5 MGD Phase I Southmost Regional Water Authority

18. Capacity Provided Southmost Regional Water Authority Total Water Sales 6,316,998,573 Annual Availability from Authority 2,737,500,000 Remaining Supply from Participant 3,579,498,573

19. Planned Brackish GW Projects North Alamo WSC (5-10 MGD) North Alamo WSC (5-10 MGD) City of Edinburg (5 MGD) City of Edinburg (5 MGD) City of Raymondville (~2 MGD) City of Raymondville (~2 MGD) City of Combs (~0.5 MGD) City of Combs (~0.5 MGD) Laguna Madre WD (2-3 MGD) Laguna Madre WD (2-3 MGD)

20. Implementation Challenges Proving up the supply Proving up the supply Concentrate Disposal Concentrate Disposal Well Design Considerations Well Design Considerations

21. Proving Up the Supply Initial Modeling Initial Modeling Test Drilling Test Drilling Development of Geologic Framework Development of Geologic Framework Long-Term Aquifer Testing Long-Term Aquifer Testing Refinement of the Model Refinement of the Model Locating Suitable Well Sites Locating Suitable Well Sites

22. Concentrate Disposal Discharge to brackish surface water Discharge to brackish surface water Discharge to ocean Discharge to ocean Injection Injection Waste water systems Waste water systems Evaporative Evaporative

23. Well Design Considerations Corrosion Protection Corrosion Protection Casing Design Casing Design –Stainless Steel –PVC –Carbon Steel –Fiberglass –Coatings Pump Column Design Pump Column Design –Stainless Steel –PVC –Fiberglass Pump Construction Materials Pump Construction Materials –Bowls and Motors - Stainless Steel –Impellers - Brass/Stainless Steel/Ceramic

24. Brackish groundwater is the least cost alternative for each entity Brackish groundwater is the least cost alternative for each entity Regional Advantages Regional Advantages –Economy of Scale –Personnel cost savings –Common well field –Potential for additional partners –Favorable grant potential Summary and Conclusions

25. Cost Factors Cost Factors –Improvement in Membrane Technology –Operation of RO at peak capacity –Increasing expense of surface water treatment and water rights Water Quality Improvement Water Quality Improvement Decreased Competition Decreased Competition Summary and Conclusions

26. Questions?